Sickle cell disease (SCD) is a major health problem, affecting approximately 1 in 400 African Americans. Although newborn screening and improvements in medical care have resulted in more favorable long- term prognosis, most people with this disease still encounter frequent unpredictable episodes of pain over their life span. Although some people cope will with pain, others suffer significant vocational and psychosocial dysfunction and become overly dependent upon health care services. The aim of this proposal is to evaluate the role of daily stress, positive and negative mood, and daily coping in SCD pain. Although clinicians and patients have long suspected a link between stress, mood, and pain, the variables have not been empirically studied. Participants in the proposed studies will be 60 adults and 60 adolescents with SCD. Participants will complete daily diaries in which they will track closely day-to-day fluctuations in stress, mood, and pain. Powerful, multi-level modeling analyses will be used to carefully examining the temporal sequencing of these variables. The hypotheses to be tested are: (1) that increased daily stress and negative mood will be associated with more frequent and severe pain on the same day and on subsequent days, whereas positive mood will predict less same-day and subsequent-day pain; (2) that increased daily stress and negative mood will be associated with greater decreases in school/work activity and more health care contacts on pain days, whereas positive mood in the presence of pain will predict better outcome; and (3) that those individuals will who have the combination of high daily stress, high negative mood, and poor daily coping will have the most difficulties in these areas, whereas those with positive mood and active coping will have better overall adjustment. These dairy studies are innovative and may help to establish a temporal link between stress, mood, and the course of pain in naturalistic situations. The use of comparable methodologies in adults and adolescents will facilitate an examination of stress/mood/pain linkages across two age groups. Ultimately, this research will help improve pain management interventions. Stress and mood management may be important additions to cognitive-behavioral interventions. Stress and mood management may be important additions to cognitive behavioral pain management interventions. Improved interventions might actually help patients to prevent SCD pain, use health care more efficient, and improve the quality of their lives.